I have a pretty big patch of blackberries. A patch we want to keep as it has the big juicy blackberries as my 3 three year old says. The patch is out of control its about 12 feet high and 20 feet long. It is taking over the blueberry bush. How should I trim it for the top down or take out the stems form the ground. And can If i put the stems in the ground in another area will they grow or is that a waste of time.